Shaped sanitary napkin with flaps

ABSTRACT

A shaped sanitary napkin. The sanitary napkin of this invention has an absorbent means, such as an absorbent core, and two flaps extending outwardly from the absorbent means. Each flap is associated with the absorbent means along a nonlinear line of juncture and each has two axes of flexibility. In use, the absorbent means is secured in the crotch of a panty and the flaps are secured about the elastic edges of the panty so that, when the panty is worn, the absorbent means is held adjacent the body while the flaps form a wall at each side of the absorbent means and seals against the body. Both the walls and the seals serve to prevent soiling of the body and clothing by menstrual fluid.

This is a division of application Ser. No. 07/054,716, filed on May 22,1987, now U.S. Pat. No. 5,267,992 which is a continuation of applicationSer. No. 06/789,914, filed on Oct. 17, 1985, which is a continuation ofapplication Ser. No. 07/591,620, now U.S. Pat. No. 4,687,478 filed onMar. 20, 1984; which is a continuation-in-part of application Ser. No.07/511,118, filed on Jul. 5, 1983 now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to absorbent devices. More particularly, itrelates to sanitary napkins.

2. Background Art

Sanitary napkins are absorbent devices designed to receive and containvaginal discharges such as menses. They are omnipresent items of modernsociety. In recent periods, disposable sanitary napkins designed to beheld adjacent to the human body through the agency of a garment, such asan undergarment or panty, have effectively supplanted the moretraditional type of sanitary napkin which required a specially designedbelt for use.

Clark, in U.S. Pat. No. 2,787,271 issued on Apr. 2, 1957, describes asanitary napkin comprising a rectangular central pad and a pair oflateral flaps fabricated integrally with the pad. These flaps areadapted to fold downwardly and bear against the opposed inner surfacesof the thighs of the wearer to arrest any overflow from the central padwhich would normally stain clothing. This sanitary napkin is sofabricated that the lateral flaps will bend downwardly along straightparallel hinge lines defining the respective sides of the central pad.The central pad has a core body which is a soft, absorbent, fibrousmaterial, such as absorbent cotton, and which extends withoutinterruption into the lateral flaps. The hinges are formed bycompressing (as by steam pressing with relatively sharp-edged pressingtools) along the lateral margins of the core body in the central pad.

Rickard, in U.S. Pat. No. 3,397,697 issued Aug. 20, 1968, describes adisposable sanitary shield for undergarments. This device comprises anelongate sheet of flexible material divided into at least two panelswhich are joined by an intermediate neck-like portion. The edge portionsof one of the panels adjacent the neck-like portion comprises opposedwing-like flaps adapted to be folded over each other and to confine andencircle the crotch portion of a panty undergarment. The width of thecrotch portion of the panty is thus restricted by an encirclingabsorbent band which is in freely slideable relationship with the crotchportion of the panty.

McNair, in U.S. Pat. No. 4,285,343 issued Aug. 25, 1981, describes asanitary napkin comprising a central elongate absorbent pad elementhaving side panels extending laterally therefrom. The side panels may beformed either integrally with the central element or they may be formedseparately and secured to the longitudinal edges of the centralabsorbent pad. Lines of common juncture between the central element andthe side panels must be flexible so that each side panel can be foldedabout the respective lateral edge of the central absorbent pad andtoward the backside of the central element when the device is used. Inuse, the central element is adhesively secured to the innerside of thecrotch portion of the undergarment and each side panel is folded over toencompass at least half of the outer surface of the crotch portion ofthe undergarment.

SUMMARY OF THE INVENTION

The present invention is of an absorbent device comprising an absorbentmeans and two flaps extending outwardly from the absorbent means. Eachof the flaps is associated with the absorbent means along a nonlinearline of juncture and has a free distal edge remote from the line ofjuncture. Each of the flaps includes two axes of flexibility; the firstis intermediate the line of juncture and the distal edge while thesecond is intermediate the first axis and the distal edge.

A preferred embodiment of the present invention is a sanitary napkincomprising an absorbent means having two opposed longitudinal edges, afluid pervious body contacting surface, and an opposed liquid impervioussurface. It also comprises two flaps, one extends outwardly from eachlongitudinal edge of the absorbent means. Each of the flaps is, asabove, associated with the absorbent means along a nonlinear line ofjuncture and has a free distal edge remote from the line of juncture.Each of the flaps includes two axes of flexibility; the first isintermediate the line of juncture and the distal edge while the secondis intermediate the first axis and the distal edge. The first axis isadapted to allow independent rotation of the distal edge of the flap inan arc generally in the direction from the liquid impervious surfacetoward the fluid pervious body contacting surface while the second isadapted to allow rotation of the distal edge in an arc generally in thedirection from the fluid pervious body contacting surface toward theliquid impervious surface.

In preferred embodiments, the flaps are flexible essentially over theirentire surface thereby providing an infinite number of axes offlexibility. In other embodiments, at least one of the axes is uniquelydefined by distinct structural features.

Optionally, and preferably, adhesive attachment means are provided onthe absorbent means and each of the flaps to secure the device in thecrotch portion of an undergarment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a preferred embodiment of a sanitary napkin ofthe present invention.

FIG. 2 is a cross sectional view of the sanitary napkin of FIG. 1 takenalong line 2--2 of FIG. 1. The thicknesses of certain elements have beenexaggerated for clarity.

FIG. 3 is a plan view of an alternate embodiment of a sanitary napkin ofthe present invention.

FIG. 4 is a cross sectional view of the sanitary napkin shown in FIG. 3taken along line 4--4 of FIG. 3. The thicknesses of certain elementshave been exaggerated for clarity.

FIG. 5 is a front view of a conventional panty in which the sanitarynapkin of the present invention can be used.

FIG. 6 is a cross sectional view of the panty of FIG. 5 taken along line6--6 showing the sanitary napkin of FIG. 1 disposed therein.

FIG. 7 is a fragmentary coronal view showing the sectioned sanitarynapkin and panty of FIG. 6 in place on a user.

DETAILED DESCRIPTION OF THE INVENTION

While the present specification concludes with claims particularlypointing out and distinctly claiming that which is regarded as theinvention, it is believed that the present invention can be more readilyunderstood through study of the following specification and of theappended drawings.

A preferred embodiment of a sanitary napkin of the present invention isshown in FIGS. 1 and 2. Sanitary napkin 210 comprises an absorbent meansrepresented by central absorbent pad 212 and two flaps 224 and 224'. (Inthe discussion that follows, unless otherwise noted, the sanitarynapkins will have two flaps. While it is not necessary that the flaps beidentical, or, more properly, mirror images one of the other, theypreferably are. Thus the description of the first will be a descriptionof the second. Discussion of the second will therefore, be omitted forclarity of exposition. Corresponding elements are indicated in thedrawings by reference numerals and primed reference numerals.)

Flap 224 is associated with central absorbent pad 212 along nonlinearline of juncture 226. As used in the context of the presentspecification, the term "nonlinear" refers to any of various curved, asopposed to straight, lines.

Flap 224 has distal edge 278 which is remote from line of juncture 226.In the embodiment illustrated In FIG. 1, line of juncture 226 is concaverelative to distal edge 278. That is to say, line of juncture 226 curvesaway from distal edge 278. In this embodiment, nonlinear lines ofjuncture 226 and 226' and seam 239 define an absorbent means (centralabsorbent pad 212) which is narrower in its central region than at itsends. A sanitary napkin narrower in the center than at the ends isgenerally perceived by the user as more comfortable than a sanitarynapkin of uniform width.

Flap 224 is provided with first axis of flexibility 256 and second axisof flexibility 234.

FIG. 2, a cross sectional view of sanitary napkin 210 taken along line2--2, illustrates generally the preferred construction for sanitarynapkin 210. As shown in FIG. 2, central absorbent pad 212 comprisesabsorbent core 216. Central absorbent pad 212 and flap 224 both comprisetopsheet 214. Backsheet 218 is disposed on the side of absorbent core216 and flap 224 opposite that of topsheet 214. In effect, topsheet 214forms one surface of flap 224 while backsheet 218 forms the othersurface; topsheet 214 also forms one surface of central absorbent pad212, backsheet 218 the other.

In the embodiment illustrated, flap absorbent core 230 interposedbetween topsheet 214 and backsheet 218. For simplicity of construction,flap absorbent core 230 extends throughout napkin 210 and is interposedbetween absorbent core 216 and backsheet 218. While this is a preferredembodiment primarily for reasons of construction, it is not necessarythat flap absorbent core 230 be interposed between absorbent core 216and backsheet 218.

Topsheet 214 and backsheet 218 are joined at seam 239 around the entireperiphery of sanitary napkin 210. The purpose of this seam is to unitethe various elements of the sanitary napkin into a whole. Topsheet 214is secured to flap absorbent core 230 and backsheet 218 along nonlinearlines of juncture 226 and 226' by attachment means not illustrated inFIG. 2.

Illustrated in FIG. 2 are the adhesive attachment means central padadhesive 220 and flap adhesive 236 which are covered by, respectively,central pad release liner 222 and flap release liner 238. These adhesiveattachment means are adpated to secure sanitary napkin 210 within thecrotch region of an undergarment.

Topsheet 214 is liquid permeable and, when sanitary napkin 210 is inuse, is in close proximity to the skin of the user. Topsheet 214 iscompliant, soft feeling and non-irritating to the user's skin. It can bemade from any of the materials conventional for this type of use.Nonlimiting examples of suitable materials that can be used as topsheet214 are woven and nonwoven polyester, polypropylene, nylon, and rayonand formed thermoplastic films; formed films are preferred. Suitableformed films are described in U.S. Pat. No. 4,324,246 issued to Mullaneand Smith on Apr. 13, 1982 and U.S. Pat. No. 4,342,314 issued to Radeland Thompson on Aug. 3, 1982, both of which patents are incorporatedherein by reference. Formed films are preferred for topsheet 214 becausethey are pervious to liquids and yet non-absorbent. Thus, the surface ofthe formed film, which is in contact with the body, remains dry and ismore comfortable to the wearer.

In preferred embodiments of the present invention, the outer surface oftopsheet 21q Is treated with a surfactant. Treating the outer surface ofthe topsheet with surfactant renders the surface more hydrophilic whichresults in liquid penetrating the topsheet faster than if the surfacewere not treated. This diminishes the likelihood that menstrual fluidwill flow off topsheet 214 rather than being absorbed by the absorbentcore 216. It Is preferred that the surfactant be substantially evenlyand completely distributed across the outer surface of topsheet 214.This can be accomplished by any of the common techniques well known tothose skilled in the art. For example, the surfactant can be applied totopsheet 214 by spraying, by padding, or by the use of transfer rolls.

In preferred embodiments, the inner surface of topsheet 214 is securedin contacting relation to absorbent core 216. This contactingrelationship results in liquid penetrating topsheet 214 faster than ifit were not in contact with absorbent core 216. Topsheet 214 can bemaintained in contact with absorbent core 216 by applying adhesive,preferably in spaced, limited areas, to the inner surface of thetopsheet 214. Examples of suitable adhesives used for this purposeinclude the acrylic emulsion E-1833BT manufactured by Rohm and HaasCompany of Philadelphia, Pa. and the acrylic emulsion WB3805manufactured by H. B. Fuller Company of St. Paul, Minnesota. Theadhesives can be applied by the same methods as the surfactant isapplied to the outer surface of topsheet 214.

Referring to FIG. 2, it can be seen that absorbent core 216 ispositioned between topsheet 214 and backsheet 218. Absorbent core 216provides the means for absorbing menstrual fluid. Absorbent core 216 isgenerally compressible, conformable, and non-irritating to the user'sskin. It can comprise any material used in the art for such purpose.Examples of suitable materials are layers of tissue (such as wadding)and fibrated comminution pulp (airfelt), with fibrated comminution pulpbeing preferred.

Backsheet 218 is impervious to liquids and, thus, prevents menstrualfluid which may be expressed from absorbent core 216 from soiling theclothing of the user. Any material used in the art for such purpose canbe utilized herein. Suitable materials are embossed or nonembossedpolyethylene films and laminated tissue.

The outer surface of backsheet 218, generally in register is withabsorbent core 216, is coated with central pad adhesive 220. Central padadhesive 220 provides an adhesive attachment means for securing centralabsorbent pad 212 in the crotch portion of a panty. Any adhesive or glueused in the art for such purpose can be used herein, with pressuresensitive adhesives being preferred. Suitable adhesives are CenturyA305-IV manufactured by the Century Adhesives Corporation and Instant34-2823 manufactured by National Starch Company. As shown in FIG. 2,central pad adhesive 220 is generally the same width as absorbent core216; the width is not critical and appropriate widths, as well aslengths, can be readily selected by those skilled in the art. Thepressure sensitive adhesive of central pad adhesive 220 should becovered with central pad release liner 222 to keep the adhesive fromdrying out and to keep it from sticking to extraneous surfaces prior touse. Any commercially available release liner commonly used for suchpurposes can be used herein. Nonlimiting examples of suitable releaseliners are BL 30 MG-A Silox E1/0 and BL 30 MG-A Silox 4 P/O both ofwhich are manufactured by the Akrosil Corporation.

As can be observed from the foregoing discussion, central absorbent pad212 Is an absorbent means that has a fluid pervious body contactingsurface (represented in FIG. 2 by topsheet 214) and an opposed liquidImpervious surface (represented in FIG. 2 by backsheet 218). It is to beunderstood that the embodiment illustrated is only one possibleembodiment, albeit a preferred one. Other possible embodiments includeone in which an absorbent core is essentially completely wrapped withtopsheet before It is placed on a backsheet. The absorbent means canalso comprise an absorbent core which possesses sufficient integrity tostand alone and which is fluid permeable on one surface while the othersurface has been treated to render it liquid impervious.

It should be noted that a narrow central absorbent pad 212 is effectivebecause the overall configuration and use of sanitary napkin 210 resultsIn central absorbent pad 212 being maintained in close proximity to thebody. Such proximity of central absorbent pad 212 places it preciselywhere It should be: very near the body at the vaginal opening. Centralabsorbent pad 212 can then absorb the vast majority of the menstrualfluid (menses) before it has an opportunity to flow along centralabsorbent pad 212.

It is to be observed that lines of juncture 226 and 226' are the linesalong which flaps 224 and 224' are associated with the absorbent means(represented by central absorbent pad 212); as such they represent linesof demarcation between the absorbent means and the flaps. It is also tobe observed that the lines of juncture are nonlinear. Preferably, theyare concave relative to distal edges 278 and 278' and relative to thebulk of central absorbent pad 212. The absorbent means thus takes on ashape in which the width at its center is less than the width at itsends. This contoured shape is closely atuned to anatomical dimensions ofthe crotch region of the user. It makes the sanitary napkin morecomfortable to wear while, at the same time, making it more effective asby rendering it less subject to compression by the legs of the user.While nonlinear lines of juncture which are convex relative to thedistal edges and to the bulk of the central absorbent pad can be used,they are not preferred.

It is preferred that the width of central absorbent pad 212 betweenlines of juncture 226 and 226' at their nearest approach be from about 1to about 8 centimeters. The width of the central absorbent pad 212 atits ends should be from about 2 to about 9 centimeters. Centralabsorbent pad 212 should be from about 7.6 to about 38 centimeters long.

Central absorbent pad 21 2 need not have an absorbent capacity muchgreater than the total amount of menstrual fluid anticipated to beabsorbed. Thus, central absorbent pad 212, in addition to being narrow,can be relatively thin. Furthermore, a narrow and thin absorbent meansis extremely comfortable to the user. In the embodiment illustrated inFIGS. 1 and 2, topsheet 214 serves as a topsheet for flaps 224 and 224'.In general, the flaps do not require a topsheet to enable them tofunction properly, but the use of a topsheet is preferred. Flaptopsheets can be integral with the absorbent means' body contactingsurface, as illustrated, or they can be independent elements; the formeris preferred. All the specific physical property comments made aboveabout topsheet 214 apply to any flap topsheet that is used. There is,however, no requirement that the flap topsheet be the same material asthe topsheet associated with the central absorbent pad. In preferredembodiments, the flap topsheet can be a nonwoven material while thetopsheet with the central absorbent pad is a formed film.

Flap absorbent core 230 is positioned between topsheet 214 and backsheet218, most importantly in flaps 224 and 224'. In the embodimentIllustrated, flap absorbent core also underlies absorbent core 216; thisis a preferred arrangement because construction of the sanitary napkin210 is thereby facilitated. In this arrangement, the absorbent capacityof absorbent core 216 is enhanced. Flap absorbent core 230 provides ameans for absorbing menstrual fluid that is not absorbed by, or that isexpressed from, absorbent core 216. Flap absorbent core 230 is generallycompressible, conformable and non-irritating to the user's skin. It canbe made from any of the materials that can be used to make the absorbentcore 216 as described above. Preferably, flap absorbent core 230 is atissue paper sheet. While the use of a flap absorbent core is highlypreferred, it can be omitted.

In the embodiment illustrated in FIGS. 1 and 2, backsheet 218 serves asa backsheet for flaps 224 and 224'. The flaps require a backsheet (ormore generally, a liquid impervious material) to enable them to functionproperly. The flap backsheets can be integral with the absorbent meansliquid impervious surface, as illustrated, or they can be independentelements; the former is preferred. All the specific physical propertycomments made above about backsheet 218 apply to any flap backsheet.

The overall size of flap 224 can be readily selected by those skilled inthe art. Preferably, sanitary napkin 210 is from about 10 to about 23centimeters wide between distal edges 278 and 278' at their greatestseparation. Preferably flap 224 is from about 7.6 to about 18centimeters long in the direction parallel to the longitudinal axis ofthe sanitary napkin.

The outer surface of flap 224, adjacent distal edge 278, is coated withflap adhesive 236.

Flap adhesive 236 is an adhesive attachment means which is used toassist in maintaining flap 224 in position after it is wrapped aroundtie edge of the crotch portion of a panty as described below. Anyadhesive used for central pad adhesive 220 can be used as flap adhesive236. Also, flap adhesive 236 is covered with a removable flap releaseliner 238. Any release liner material used for central pad release liner222 can be used for flap release liner 238.

As shown in FIGS. 1 and 2, topsheet 214 is secured to backsheet 218along seam 239. Seam 239 can be formed by any means commonly used in theart for this purpose such as by gluing, crimping or heat sealing. Seam239 is illustrated extending completely around the periphery of sanitarynapkin 210; this is a preferred embodiment for ease of construction.(Other means of uniting the various elements of the device can be used.)Flap absorbent core 230 is illustrated as extending into seam 239; thisis, likewise, an arrangement which results from a simplifiedconstruction technique. The three elements--topsheet, flap absorbentcore, and backsheet--can be brought into register, with the absorbentcore properly positioned between them, and the seam formed and the outershape of the sanitary napkin established by cutting in one or twooperations.

Topsheet 214 can be secured to backsheet 218 (and to flap absorbent core230) along lines of juncture 226 and 226' by any of the techniques usedto form seam 239.

Flap 224 contains first axis of flexibility 256 and second axis offlexibiliity 234. These two axes of flexibility allow flap 224 to form awall, in use, as described hereinafter.

First axis of flexibility 256 is so constructed as to allow the flap tobend along first axis of flexibility 256. The direction of the bend ofthe flap is upward when sanitary napkin 210 is in the configuration ofFIG. 2. More generally, the direction of the bend is such that thatportion of flap 224 containing distal edge 278 rotates about the firstaxis of flexibility 256 in an arc beginning generally from its extendedposition, as shown in FIG. 2, toward the fluid pervious body contactingsurface of the absorbent means (as represented in FIG. 2 by that portionof topsheet 214 in register with absorbent core 216) and away from theliquid impervious surface of the absorbent means (as represented in FIG.2 by that portion of backsheet 218 in register with absorbent core 216).

Second axis of flexibility 234 is so constructed as to allow the flap tobend along second axis of flexibility 234. The direction of the bend isdownward when sanitary napkin 210 is in the configuration of FIG. 2.More generally, the direction of the bend is such that that portion ofthe flap 224 containing distal edge 278 rotates about second axis offlexibility 234 in an arc generally from its extended position, as shownin FIG. 2, toward the liquid Impervious surface of the absorbent means(as represented in FIG. 2 by that portion of backsheet 218 in registerwith absorbent core 216 as comprising central absorbent pad 212) andaway from the fluid pervious body contacting surface of the absorbentmeans (as represented in FIG. 2 by that portion of topsheet 214 inregister with absorbent core 216).

First and second axes of flexibility can be provided in various ways. Apreferred method is shown in FIGS. 1 and 2. In the embodimentillustrated, the materials of construction of flap 224 are selected sothat flap 224 is extremely flexible over essentially the whole of itsextent. Axes of flexibility of 256 and 234, as shown in FIGS. 1 and 2,are not, then, single, unique structures, but are, rather,representative of an essentially infinite number of pairs of axes. Thisarrangement is particularly preferred because it allows sanitary napkin210 to be easily adjusted, during application, to properly fit a numberof differently sized undergarments and, in use, anatomies as describedbelow.

Total flexibility of flap 224 permits flap 224 to be positioned aroundthe edge of the crotch portion of a panty without having to alter thenatural path of the edge of the crotch portion of a panty. Thus, theedge of the crotch portion of a panty need not be stretched to fit tothe second flexible axis of the flap. Furthermore, the natural path ofthe edge of the crotch portion of a panty results, when the sanitarynapkin is in place for use, in the highest wall (described below) beingformed; this, in turn, provides the greatest barrier to flow of themenstrual fluid.

In the embodiment of sanitary napkin 210 illustrated In FIGS. 1 and 2,it is preferred that the materials of construction of flap 224 beselected so that the flap has a resistance to bending, through an arc of90°, of less than about 200 grams, more preferably less than about 50grams, and most preferably less than about 25 grams as measured by thePCA Score Bend Tester manufactured by the Thwing-Albert InstrumentCompany of Philadelphia, Pa. These values are obtained when a section offlap 7.6 centimeters long (and which is maintained 2.5 centimeters abovethe bottom edge of the tilting plate of the tester) is evaluated underTAPPI standard conditions.

In the abstract, an axis is generally considered to be a linear element.The present axes of flexibility are also generally linear, but, sincethe materials from which the flaps are constructed generally possesssuch a degree of flexibility that the flaps can be bent and foldedconveniently with manual force, the axes of flexibility can becomenonlinear under the influence of external forces.

An alternate embodiment of a sanitary napkin 310 having first and secondaxes of flexibility 356 and 334 in flap 224 is illustrated in FIGS. 3and 4. (The reference numerals used in FIGS. 3 and 4 refer to the sameelements as in FIGS. 1 and 2.) In this embodiment, axes of flexibility356 and 334 are provided by severely crimping flap 224 as illustrated.Thus, flap 224 of sanitary napkin 310 contains two unique axes (orunique hinge means) along which flap 224 can bend as described inrelation to the embodiment shown in FIGS. 1 and 2. Axes of flexibility356 and 356' preferably are from about 2 to about 18 centimeters apart.Axes of flexibility 234 and 256 (and 234' and 256') are preferably fromabout 1 to about 5 centimeters apart. While this is a satisfactoryembodiment of the present invention, it is less preferred than theembodiment illustrated in FIGS. 1 and 2 because the crotch of theundergarment to which it is applied must, in general, be eitherstretched or compressed as sanitary napkin 310 is applied. Nevertheless,use of the embodiment illustrated in FIGS. 3 and 4 will result in oneobtaining essentially all the benefits associated with the use of theembodiment illustrated in FIGS. 1 and 2.

As illustrated in FIG. 1, first axis of flexibility 256 is In closeproximity to line of juncture 226. First axis of flexibility 256 can, infact, intersect the line of juncture 226 at the point the lattercontacts the outer margin of the sanitary napkin (as that margin isrepresented by seam 239). In the general case, this will be the onlysituation in which first axis of flexibility 256 and line of juncture226 touch or coincide. It is to be understood, however, that applicationof external forces during use can cause the first axis of flexibility tobe displaced toward the line of juncture so that, in some instances, thetwo can touch or coincide.

Sanitary napkins including the central absorbent pad comprising a liquidpervious topsheet, a liquid impervious backsheet, and an absorbent coreinterposed between the topsheet and the backsheet, and having a flapextending from each longitudinal edge of the central absorbent pad,wherein the line of juncture between each flap and the longitudinal edgeof the central absorbent pad is linear, and having each flap providedwith a flexible axis located in the body of the flap, can be constructedso that the sanitary napkin preferentially bends at the linear line ofjuncture of each flap and the longitudinal edge of the central absorbentpad as well as at the flexible axis located within the body of the flap.Such napkins, while distinctly different from those of the presentinvention, will function in a manner analogous to those of the presentinvention.

The precise shape of flap 224, as well as the overall shape of sanitarynapkin 210, can be selected by those skilled in the art without undueexperimentation. In the embodiments illustrated in FIGS. 1 and 3, theflaps are symmetrically disposed along the longitudinal axis of thesanitary napkin; while this is a preferred embodiment, it Is not amandatory design feature. As noted above, the flaps are generally mirrorimages one of the other; while such a situation is preferred, it islikewise not a mandatory design condition.

Further, the sanitary napkins illustrated in FIGS. 1 through 4 areembodiments wherein the flaps are formed integrally with the topsheetsand backsheets of the sanitary napkin. Once again, while this Is apreferred method of construction, it is not mandatory. Flaps and centralabsorbent means can be formed independently and joined by techniqueswell know to those skilled in the art in such a manner that theresulting sanitary napkin will function essentially equivalently to theembodiments illustrated herein.

In use, the sanitary napkins of this invention can be held in place byany support means well known for such purpose. Belts worn about thewaist of the user can be used. It is highly preferred, however, thatthey be placed in the user's panty undergarment as described below.

FIG. 5 is an undergarment of the type commonly worn by many women andwell known as a panty. It comprises front section 240, back section 242,and crotch portion 244 which joins front and back sections 240 and 242.Crotch portion 244 comprises two side edges 246 and 246' and centercrotch portion 248.

A sanitary napkin of the present invention, such as the one illustratedat 210 in FIGS. 1 and 2, is utilized by removing the release liners 222,238 and 238' and thereafter placing the sanitary napkin in a panty asshown in FIG. 6. The center of central absorbent pad 212 is placed incrotch portion 244 of the panty with one end of central absorbent pad212 extending toward front section 240 and the other end toward backsection 242 of the panty and with backsheet 218 in contact with theinner surface of center crotch portion 248 of the panty. Central padadhesive 220 maintains central absorbent pad 212 in position. The distalportions of flaps 224 and 224' are folded around. respectively, sideedges 246 and 246' of the panty by bending along second flexible axes234 and 234'. Flap adhesive 236 and 236' secure flaps 224 and 224' insuch position. Thus, flaps 224 and 224' are each folded over themselveswith a portion of the panty--including side edges 246 and246'--interposed therebetween.

Numerous benefits are derived from the use of the sanitary napkin of thepresent invention. Flaps 224 and 224' are wrapped around each edge 246and 246' of the crotch portion 244 of the panty as shown in FIG. 6. Thisencapsulation of the panty crotch assists In preventing the menstrualfluid from coming into contact with the center crotch portion of thepanty. Thus, the center crotch portion of the panty will not be soiled.

There are two other benefits. One is that the portions of the flapscontaining the second axes of flexibility, 234 and 234', provide anexcellent gasket-like seal against the body. The other is that thecentral absorbent means, such as central absorbent pad 212, ismaintained in excellent contiguous relationship to the body.

The edge of the crotch portion of a panty generally contains an elasticmaterial. When a panty is worn, the elastic of the edge of the crotchportion generates an upward force, i.e., against the body, due to theenergy in the elastic and the fit of the panty. The placement of thesecond axis of flexibility, such as second axes of flexibility 234 and234', between the body and the edges of the crotch portion of the pantyresults in the upward force generated by the edge of the crotch portionof the panty pushing the portion of the flaps containing the second axesof flexibility snugly against the body. This results in a gasket-likeseal being formed along the axes of flexibility between the flaps andthe body. This is illustrated in FIG. 7 which is a fragmentary coronalview showing the sectioned sanitary napkin and panty of FIG. 6 in placeon a user. (A coronal view is the frontal plane that passes through thelong axis of the body.) The gasket-like seal assists in preventingmenstrual fluid from penetrating beyond the second axes of flexibilitywhich, in turn, minimizes soiling of the legs and adjoining clothing.Another benefit derived from the flaps being pushed snugly against thebody along the second axes of flexibility is that the absorbent means(central absorbent pad) is forced into close proximity to and intoconformity with the body. This, too, is illustrated in FIG. 7. Themaintenance of the central absorbent pad against the body is know as"good body contact". Good body contact is beneficial because it providesa barrier to lateral flow of menstrual fluid. Without such a barrier,menstrual fluid would tend to flow quickly along the topsheet, therebyproviding less time for it to be absorbed by the absorbent core.

Inherent bunching as the formation of wrinkles along the lateral axes ofa sanitary napkin resulting from the initial placement of the sanitarynapkin in a panty for use. (Lateral axes of a sanitary napkin extendacross the "crotch portion" of the napkin generally parallel to line2--2 of FIG. 1.) This inherent bunching is due to the facts that asanitary napkin is essentially linear along its longitudinal axis andthat the anatomical contour of the body where the sanitary napkin isplaced is essentially "U" shaped. (The longitudinal axis of a sanitarynapkin extends from end to end of the central absorbent means and isgenerally perpendicular to line 2--2 of FIG. 1.) Thus, as soon as asanitary napkin is put in place, its shape is changed along itslongitudinal axis from being essentially linear to "U" shaped. Thischange in shape creates wrinkles along the lateral axes of the sanitarynapkin, with the vast majority of the wrinkles being at the point ofgreatest curvature of the body i.e. the crotch area.

Forced bunching is the wrinkling of a sanitary napkin, along either itslateral or longitudinal axes, caused by movement of the legs of theuser.

Wrinkles in a sanitary napkin created by inherent and forced bunchingare known as flow channels because menstrual fluid can easily flow alongthe trough of the wrinkle in the absence of significant body contactalong the wrinkle.

The sanitary napkin of the present invention provides numerous benefitsbecause the flaps bend at the first axis of flexibility. In particular,the benefits provided are that:

(1) inherent bunching results in flow channels being formedsubstantially only in the central absorbent pad, not the bulk of theflaps;

(2) the sanitary napkin of the present invention can withstand muchforced bunching before flow channels are created;

(3) even if the forced bunching is harsh enough to create flow channels,the channels formed will be essentially limited to the central absorbentpad; and

(4) even if the forced bunching is so great that flow channels arecreated in both the central absorbent pad and the flaps, the menstrualfluid is restrained from penetrating beyond the second flexible axes ofthe flaps.

These four benefits are obtained because the sanitary napkin of thepresent invention bends along the axes of flexibility. The anatomicalfeatures of the crotch area of a woman are such that the crotch sectionis substantially trapezoidal shaped, with the center area of the crotch,which is located at the vaginal opening, being the base of thetrapezoid. When a sanitary napkin of the present invention, such as theembodiment shown in FIGS. 1 and 2, is in use, the anatomical features ofthe crotch area force the sanitary napkin to bend upward at the firstaxis of flexibility. This results In the sanitary napkin forming a wallat each side of the central absorbent pad; the wall extends from thefirst axis of flexibility to the second axis of flexibility, asillustrated in FIG. 7. Thus, in use, the sanitary napkin of the presentinvention has a well-like shape with the plane formed by the second axesof flexibility (234 and 234') that are wrapped around the edge of thecrotch portion of the panty (246 and 246') being higher than the planeformed by the first axes of flexibility (256 and 256') when the user isin an upright position.

Inherent bunching in the sanitary napkin of the present invention issubstantially limited to the central absorbent pad; essentially no flowchannels are formed in the walls. Without being bound by any theory, itis believed that when the flow channels are being formed, the energycreating them is transmitted across the central absorbent pad and theflow channels are extended. This proceeds until the flow channels reachthe first axes of flexibility. The flow channels extend no farther thanthis because, it is believed, the first axes of flexibility relieve theenergy extending the flow channels. Thus the flow channels will notreach the gasket-like seal formed between the flap and the body at thesecond axis of flexibility, and, therefore, the seal will remain intact.The gasket-like seal forms a dam and blocks the flow of the menstrualfluid. The menstrual fluid can then be absorbed (or reabsorbed) by theabsorbent core.

The sanitary napkin of the present invention can withstand much forcedbunching before any flow channels are created, because the energytransmitted to the sanitary napkin by the forced bunching results in thewalls tending to rotate around each first axis of flexibility. Withoutsuch rotation flow channels would be formed.

Even if the forced bunching is harsh enough to create flow channels, thechannels will be substantially limited to the central absorbent pad.This is true for the same reasons that inherent bunching forms flowchannels only in the central absorbent pad. Therefore, the gasket-likeseal will remain intact and form a dam and block the flow of themenstrual fluid until it can be absorbed by the absorbent core.

Even if the forced bunching is so great that flow channels are createdin both the central absorbent pad and the flaps, menstrual fluid isrestrained from penetrating beyond the second axes of flexibility of theflaps. Such flow channels are likely to break the gasket-like seal.However, menstrual fluid is restrained from penetrating beyond thesecond flexible axes of the flaps because the walls themselves will forma barrier to flow of menstrual fluid. Menstrual fluid would have to flowup the walls, which is substantially directly against the force ofgravity when the user is in an upright position, in order to penetratethe break in the gasket-like seal. Thus the walls themselves restrainthe flow of the menstrual fluid.

In summary, the sanitary napkin of the present invention forms flowchannels essentially only in the central absorbent pad which results inthe gasket-like seal remaining intact. Thus, menstrual fluid will notflow beyond the gasket-like seal. However, if the forced bunching is sogreat that the gasket-like seal breaks, the walls themselves restrainthe flow of the menstrual fluid.

It is important to note that only a minimal amount of flap absorbentcore 230, or even no flap absorbent core at all, is not inimical to theprevention of soiling by the menstrual fluid. This is due to the factthat the primary function of the walls formed by the flaps is mensturalfluid containment rather than absorbency. The central absorbent meansabsorbs the vast majority of the menstrual fluid. Furthermore, a minimalamount of flap absorbent core is much less bulky and, therefore, morecomfortable to the user.

It is also important to note that in FIG. 7 flap adhesive 236 isillustrated as contacting the edge of the panty only on its "outer"surface. While this is a preferred way of securing the sanitary napkinin the panty, flap adhesive can contact the edge of the panty on onlyits "inner" surface or both its "inner" and "outer" surfaces so long asa portion of the flap extends around and about the edge of the panty.

The sanitary napkin of this invention has been described as a devicewhich has two flaps which, in use, each form a wall. While thoseembodiments are highly preferred, devices having only one flap can beenvisioned. This one flap would be associated with the central absorbentmeans along a nonlinear line of juncture. The flap would contain atleast two, and preferably at least four, axes of flexibility which wouldallow it to form both walls described above as it is folded completelyaround the crotch portion of a panty. The flap would then be associatedwith the central absorbent means along a nonlinear line of junctureopposite the one mentioned above.

In the embodiments of the sanitary napkin of this invention, illustratedand discussed above, adhesive attachment means were present near thedistal edges of the flaps and in register with the central absorbentpad. These elements, designed to hold the sanitary napkin securely tothe crotch region of an undergarment, are highly preferred elements.Without detracting from that position, it can be asserted thatembodiments of the present invention which effectively lack one or moreof the described adhesive attachment means are also useful, novel,effective devices.

The embodiment illustrated in FIGS. 1 and 2 can be readily adpated tofunction as an embodiment of the present invention which is effectivelyfree of one or more of the adhesive attachment means.

For example, central pad adhesive 220 (and, naturally, its associatedcentral pad release liner 222) can be omitted from sanitary napkin 210illustrated In FIGS. 1 and 2. In use, this modified embodiment would beplaced in the interior crotch region of a panty, just as the unmodifiedembodiment, except that central absorbent pad 220 is not secured to theinterior crotch region of the panty. Flaps 224 and 224' can be securedabout the elastic edge of the panty as described above with flapadhesive 236 and 236'. The panty with its associated modified sanitarynapkin would then be donned by the user as before. Flap adhesive 236 and236' in cooperation with the elastic edges of the panty hold themodified sanitary napkin in place.

In a like manner, sanitary napkin 210 can be modified by omitting onlyflap adhesive 236 and 236' (and release liners 238 and 238'). Themodified sanitary napkin would be secured in the crotch region of thepanty with central pad adhesive 220 and the flaps would be merely foldedabout the elastic edges.

In a like manner, sanitary napkin 210 can be modified by omitting allflap and central pad adhesives. In use, such a modified sanitary napkinwould be maintained in position soley by cooperation among the flaps,the elastic edges of the panty, and the user's body,

Two points must be stressed in the immediately preceding discussionabout modified embodiments of the present invention.

First, only adhesive attachment means are omitted from the modifiedsanitary napkins, All other necessary elements of the device--absorbentmeans, flaps, nonlinear lines of juncture, first and second axes offlexibility-are required.

Second, the modified sanitary napkins were described generally as being"effectively free" of adhesive attachment means. The state of being"effectively free" can be achieved by completely omitting adhesiveattachment means during manufacture of the device as described. It canalso be achieved by applying complete sanitary napkin 210, asillustrated in FIGS. 1 and 2, to the panty with one or more of theadhesive attachment means covered with release liner. Sanitary napkin210 applied thusly would function essentially as if the covered adhesiveattachment means were not present. The benefits of a totally orpartially free floating sanitary napkin could then be obtained.

It will be understood by those skilled in the art that the invention hasbeen described with reference to exemplary embodiments and thatvariations and modifications can be effected in the describedembodiments without departing from the scope and spirit of theinvention.

What is claimed is:
 1. A sanitary napkin of the type for placement in anundergarment, the sanitary napkin comprising:a central absorbent padcomprising a liquid pervious pad topsheet, a liquid impervious padbacksheet joined with said pad topsheet, and an absorbent corepositioned between said pad topsheet and said pad backsheet, saidcentral absorbent pad having a pair of longitudinal edges; and a flapextending outwardly from each longitudinal edge of said centralabsorbent pad a length sufficient to be positioned around an edge of theundergarment, each said flap being associated with said centralabsorbent pad along a line of juncture, each said flap comprising aliquid pervious flap topsheet and a liquid impervious flap backsheet;wherein said pad topsheet comprises a formed film and each said flaptopsheet comprises a nonwoven material.
 2. The sanitary napkin of claim1 wherein said topsheet comprises a formed thermoplastic film.
 3. Thesanitary napkin of claim 1 wherein said backsheet is integral with eachsaid flap backsheet.
 4. The sanitary napkin of claim 1 wherein each saidflap additionally comprises a flap absorbent core positioned betweensaid flap topsheet and said flap backsheet.
 5. A sanitary napkin of thetype for placement in an undergarment, the sanitary napkin comprising:acentral absorbent pad having a pair of longitudinal edges, a centralregion, and a pair of ends, said central region having a width less thanthe width of said ends, said central absorbent pad comprising a liquidpervious topsheet; a liquid impervious backsheet joined with saidtopsheet; and an absorbent core positioned between said topsheet andsaid backsheet; and a flap extending outwardly from each longitudinaledge of said central absorbent pad in said central region a lengthsufficient to be positioned around an edge of the undergarment, eachsaid flap being associated with said central absorbent pad along a lineof juncture, each said flap possessing a free distal edge remote fromsaid line of juncture, and each said flap including an axis offlexibility intermediate said line of junction and said distal edge. 6.The sanitary napkin of claim 5 wherein said central region of saidcentral absorbent pad has a width of from about 1 centimeter to about 8centimeters.
 7. The sanitary napkin of claim 5 wherein said absorbentcore has an hourglass shape.
 8. The sanitary napkin of claim 7 whereinsaid flaps are each connectively associated with said central absorbentpad along a nonlinear line of juncture.
 9. The sanitary napkin of claim8 wherein each said line of juncture is concave.